Yang Walt, Foreman Madison M, Ly Tiffany C, Wilson Kevin R, Neumark Daniel M
Department of Chemistry, University of California Berkeley CA 94720 USA
Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA.
Chem Sci. 2025 May 30;16(25):11608-11618. doi: 10.1039/d5sc01636c. eCollection 2025 Jun 25.
Molecular beam scattering experiments are carried out to study collisions between Ne atoms ( = 24.3 kJ mol) and the surface of a cold salty water (8 m LiBr, 230 K) flat jet. Translational energy distributions are collected as a function of scattering angle using a rotatable mass spectrometer. Impulsive scattering and thermal desorption contribute to the overall scattering distributions, but impulsive scattering dominates at all three incidence angles explored. Highly super-specular scattering is observed in the impulsive scattering channel that is attributed to anisotropic momentum transfer to the liquid surface. The thermal desorption channel exhibits a cos angular distribution. Compared to Ne scattering from dodecane, fractional energy loss in the impulsive scattering channel is much larger across a wide range of deflection angles. A soft-sphere model is applied to investigate the kinematics of energy transfer between the scatterer and liquid surface. Fitting to this model yields an effective surface mass of 250 amu and internal excitation of 11.8 ± 1.6 kJ mol, both of which are considerably larger than for Ne/dodecane. It thus appears that energy transfer to cold salty water is more efficient than to a dodecane liquid surface, a result attributed to the extensive hydrogen-bonded network of liquid water and roughness of the liquid surface.
开展了分子束散射实验，以研究氖原子（ = 24.3 kJ/mol）与冷盐水（8 m LiBr，230 K）平面射流表面之间的碰撞。使用可旋转质谱仪收集作为散射角函数的平动能量分布。脉冲散射和热脱附对整体散射分布有贡献，但在所有研究的三个入射角下，脉冲散射占主导。在脉冲散射通道中观察到高度超镜面散射，这归因于向液体表面的各向异性动量转移。热脱附通道呈现出余弦角分布。与氖从十二烷的散射相比，在很宽的偏转角范围内，脉冲散射通道中的能量损失分数要大得多。应用软球模型研究散射体与液体表面之间能量转移的运动学。对该模型进行拟合得到有效表面质量为250 amu，内部激发为11.8±1.6 kJ/mol，两者均明显大于氖/十二烷体系。因此，能量转移到冷盐水似乎比转移到十二烷液体表面更有效，这一结果归因于液态水广泛的氢键网络和液体表面的粗糙度。
